The peoples of the Maghreb have some Pleistocene roots

The Maghreb is an important and interesting place. In the history of Western civilization, the tension between Carthage, the ancient port city based out of modern-day Tunisia, and Rome, is one of the more dramatic and tragic rivalries that has resonances down through the ages. Read Adrian Goldsworthy’s chapter on the Battle of Cannae in The Punic Wars for what I’m alluding to (and of course there was Cato the Younger’s dramatic remonstrations).

Later Roman Africa, which really encompassed northern Morocco, coastal Algeria, and Tunisia and Tripolitania, became a major social and economic pillar of the Imperium. Not only did men such as the emperor Septimius Severus and St. Augustine have roots in the region, but these provinces were a major economic bulwark for the Western Empire in its last century. The wealthy Senators of the 4th and 5th century were often absentee landlords of vast estates in North Africa. The fall of these provinces to the Vandals and Alans in the 430s began the transformation of the Western Empire based in Rome into a more regional player, rather than a true hegemon (perhaps an analogy here can be made to the loss of Anatolia by the Byzantines in the 11th century).

Another important aspect of North Africa is that it is the westernmost extension of the region possibly settled by Near Eastern farmers in Africa. The native Afro-Asiatic Berber languages seem to have been dominant in the region despite the influence and prestige of Punic and Latin in the cities when Muslim Arabs conquered the region in the late 7th century. The genetic-demographic characteristics of the region are relevant to attempts to understand the origins of the Afro-Asiatic languages more generally since Berber is part of the clade with the Semitic languages.

They retrieved some genotypes from a site in northern Morocco, Taforalt, which dates to ~15,000 years before the present. This is a Pleistocene site, before the rise of agriculture. The Taforalt individuals are about 65% Eurasian in affinity, and 35% Sub-Saharan African. This confirms that the Eurasian back-migration to northern Africa predates the Holocene, just as many archaeologists and geneticists have reported earlier.

The samples from the preprint date to a later time. IAM in the samples dates to 7,200 years before the present, and KEB to ~5,000 years before the present. It seems pretty clear that the IAM samples in the preprint exhibit continuity with the Taforalt samples. Though it is not too emphasized in the preprint the lower K’s seem to strongly suggest that the IAM samples have Sub-Saharan African ancestry, just like the Taforalt samples which are nearly 8,000 years older. In the KEB samples, the fraction drops, probably diluted in part by ancestry related to what we elsewhere term “Early European Farmer” (EEF), related to the Anatolian farming expansion.

Both the Taforalt and IAM samples, in particular, seem to exhibit strong affinities to Natufian/Levantine peoples. Additionally, many of these samples carry Y chromosome haplogroup E1b, just like some of the Natufians. These results indicate that the Natufian-North African populations were exchanging genes or one cline rather deep in the Pleistocene.

Though various methods have suggested that there is a lot of recent Sub-Saharan African admixture, dating to the Arab period, in North Africa, these results suggest that much of it is far older. The Mozabites, as an isolated Berber group, reflect this tendency. Though some individuals have inflated African ancestry due to recent admixture, much of it is older and evener. And yet the Mozabites seem to have less Sub-Saharan African ancestry on average than the IAM sample.

There aren’t enough data points to make a strong inference about the temporal transect, but these few results imply a decline in Sub-Saharan ancestral component after the Pleistocene with further farming migration, and then a rise again with the trans-Saharan slave trade during the Muslim period. Another issue, highlighted in the preprint, is likely heterogeneity within the Maghreb in ancestry (lowland populations in modern North Africa tend to have more Sub-Saharan ancestry due to where slaves were settled).

In the Science paper the authors make an attempt to adduce the origin of the Sub-Saharan contribution to the Taforalt individuals. The result is that there is no modern or ancient proxy that totally fits the bill. These individuals have affinities to many Sub-Saharan African populations. The Sub-Saharan component is likely heterogeneous, but attempts to model European genetic variation during the Ice Age ran into trouble that divergence from modern populations was quite great. Until we get more ancient DNA there probably won’t be too much more clarity.

On the issue of the Eurasian ancestry, it’s clearly quite like the Natufians. But curiously the authors find that the Neanderthal ancestry in these samples is greater than that found in early Holocene Iran samples. From this, the authors conclude that they may have had a lower fraction of “Basal Eurasian” (BEu) than those populations further to the east. But already 15,000 years ago BEu populations were mixed with more generic West Eurasians to generate the back-migration to Africa. If BEu diverged from other Eurasians >50,000 years ago, then it may have merged back into the “Out-of-Africa” populations around or before the Last Glacial Maximum, ~20,000 years ago.

Finally, the authors looked at some pigmentation genes. Curiously the Taforalt and IAM individuals did not carry the derived variants for pigmentation found in many West and South Eurasians, but the KEB did. This confirms results from Europe, and population genomic inference in modern samples, that selection for derived pigmentation variants is relatively recent in the Holocene.

I do want to add that one possibility about the Sub-Saharan ancestry in the Taforalt, and probably all modern North Africans to a lesser extent, is that it is ancient and local. We now know proto-modern humans were present in the region >300,000 years ago. Northwest Africa may have been part of the multi-regional metapopulation of H. sapiens, as opposed to the Eurasian biogeographic zone that it is often placed, before a post-LGM back migration of Eurasians.

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13 thoughts on “The peoples of the Maghreb have some Pleistocene roots”

What are the implications of wet Sahara periods on all of this? Would gene flow between sub-Saharan Africa and North Africa be much easier? Would a wet Saharan population provide genes to both shows off the Sahara, explaining relationships?

Can we expect anymore forthcoming DNA studies from Ancient Egypt? Considering this evidence of Eurasian-back-flow coincides with the development of agriculture in the Nile Valley and the spread of Afroasiatic languages, it would answer a great deal.

What do you expect Old Kingdom/Early Dynastic Egyptians to look like ancestrally? West Eurasian vs SSA percentages? In the case of the former, would you expect a similar Natufian-esque component as Iberomaurusians?

So much for the idea then that Berbers are “refugees from Western Europe during the Younger Dryas”. If that were the case, significant Western Hunter Gatherer ancestry would have been detected (preprint).
(Younger Dryas = brief return of ice age around 10000 BC)

Very small sample size, but Pleistocene E-M78 > Neolithic E-L19 (pre-M81) bears mention, in connection with Afroasiatic phylogeny + Natufian links (even if it’s not as dramatic a change as the differences in autosomal composition). Unlike E-M78 (which is more of a signature of NE African populations, and is deeply diverged from what we think is the distinctive Y signal of the Natufians), E-L19 is E-Z830’s direct sibling.

Whether their common ancestor, E-Z827, is associated with the dispersal of a Berber-Semitic branch, or with Proto-Afroasiatic more generally, is an open question — afaik, the divergence of Berber and Semitic is unlikely to be as early as divergence of E-L19 and E-Z830.

In any case, it suggests that Egyptian is the outgroup among the Erythrean languages, and that the Natufian-related antecedent of Berber didn’t find its way to the Maghreb till the Neolithic.

It’s obvious that the founding stock of Egypt were Neolithic Levantines or a similar population at most. All reliable evidence on the development of Egyptian agriculture points to it being born from agriculture as practiced in the Levant/Fertile Crescent. Significant agriculture arose too early compared to the rest of the continent for it to be just African, and since Pots Not People has been taking such heavy blows from ancient DNA we should recognize a case of migration.

The sub Saharan component seems to be distinct from though related to modern west African populations. I wonder how it would compare to Nazlet Khater and the Jebel Sahaba populations. At last some answers, it’s getting interesting!

The North African results are pretty interesting indeed. Shows that HG ancestry might have been better “very locally” preserved in North Africa than e.g. “mainland” Europe in the long run where the vast majority of it today looks to ultimately be via the steppe bounce-back.

Their overall ancestry follows the similar complexity we see elsewhere of course with the earliest samples populations acquiring admixture from later migrations from the Near East, Europe and sub-Saharan West Africa – the one we do know about – to get us to the moderns. A decently long way since the Iberomaurusian but very cool.